Machine for making metallic tubing



A ril3,1928. j 1,664,976 'F.HANFF MACHINE FUR MAKING METALLIC TUBINGFiled oct. 16 1925 [Iilj i i 6 I 1 I 23 iiii 2/ I 2a" I 76 1 H iiPatented Apr. 3, 1928.

UNITED STATES PATENT OFFICE.

FERDINAND HANFF, F BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOB TOSIEMENS-SCHUCKERTWERKE GESELLSGHAF'I. MIT BESCHRKNKTEB HAI'TUNG, 01'SIEMENSSTADT, NEAR BERLIN, GERMANY, A CORPORATION OF GERMANY.

MACHINE FOR MAKING METALLIC TUBING.

Application filed October 16, 1925, Serial No. 62,829, and in GerinanyDecember 1, 1924.

My invention relates to a machine for making metallic tubing or forpresslng a seamless metallic sheath around cables.

I In the hitherto employed tubeor sheath- 5 making machines having asingle or a plurality of pressing-cylinders it is necessary to interruptthe operation for the purpose of charging the pressing-cylinders withplastic or molten metal. interruption the quality of the tube or thecable sufiers because the place where the metal came to rest, known asthe bambooring, which is formed in the die when the machine is stoppedhas a strong tendency to break, particularly in the caseof thinwalledtubes or sheaths. The electric qualities of the cable to be sheathed arefurther more liable to be injured because the cable is during the timeof stoppage of the machine heated by the hot metal beyond the normaltemperature at theplace located in the die.

It has been attempted to eliminate the detrimental effect of theinterruption of the process by continuing the pressing action slowly orintermittently immediately after introducing a new charge and before theliquid metal in the press cylinder has cooled down. This method is,however, not able to eliminate the detrimental effect of theinterruption in the operation of the machine.

It has also been proposed to employ metal presses with twopressing-cylinders and two plungers which operate alternately so that a35 charging of the press cylinders is possible without interrupting theoperation of the machine. l/Vith this arrangement no satisfactoryresults were obtained because it was temporarily necessary to keep bothpistons in action to obtain a good passage from the work of one pistonto that of the other.

The object of my invention is to avoid the drawbacks attached to thehitherto known tube or sheath making methods.

With this and other ends in view my invention consists essentially inproviding two or more plungers which work in one pressing-cylinder uponthe plastic liquid metal contained therein, at least one of whichlungers can be temporarily stopped and its cylinder closed forrecharging while the other plungers continue to operate. In this case acontinuous pressing takes place without the flow of the material bemgdiscon- Owing to this tinned or without the uniformity of the tube orthe sheath being detrimentally afiected during the passage from the workof one piston to that of the other.

One embodiment of my invention is shown in longitudinal vertical sectionin the draw- 00 mg. I

Referring to this figure, 11 designates a die block in which the die 12for the issuing metal is arranged. Upon this block is mounted thecylinder block 13 enclosing the chamber 14 which contains the metal. Inthe cylinder-block 13 are inserted the two steel bushings or liners 15and 16 with'th'e cylinder bores 17 and 18, shown here axially at rightangles to each other. The steel liners are adapted to be heated orcooled by theg'ackets 19 and 20. In the liners move the plungers 21 and22. The cylinder bore 18 is adapted to be closed by a slide 24. Thecharging of the machine with fresh metal-76 takes lace through chargeopening 25 with the sllde closed after withdrawal of the plunger orpiston 22 sufiiciently to expose the charge opening. The finished tubeor the cable sheath issues from the die 12. For actuating the-stop slide24 a threaded spindle 23 with handwheel is provided in the embodimentillustrated. It is, however, obvious that other equivalent means may beemployed to accomplish the purpose of tem- 35 I porarily shutting oficylinder 16 from communication with metal chamber 14.

The machine operates in the following manner: The machine is chargedwith a liquid metal, the temperature of which is kept :9 at the desiredheight by the aid of the cooling or heating jackets previouslymentioned. When pressure is applied to the plunger 21 a pressure isexerted upon the charge of metal in the chamber 14 under the action ofwhich the metal issues through the die 12 in the center of which forinstance the cable to be sheathed is located, (not shown). Diestructures of this kind are known in-the art and the detail illustrationand description there- 1 of is therefore omitted. The plunger 21 then,under the pressure exerted, descends slowly. When the stock of metal inthe cylinder 17 has been reduced to a certain extent the cylinder 18 isclosed by the slide 24, the plunger 22 is withdrawn and the cylinder 18is charged with fresh metal through the charge opening 25. When thecharge has been introduced the slide is opened again and the plunger 22pushed forward. By the flow of the metal from the cylinder 18 into themetal chamber 14 and the cylinder 17 under high pressure the piston 21is raised into its upper position without the squirting of the metalfrom the die 12 being-in terrupted. When the feeding stroke of piston 22is completed the piston 21 has again arrived in its uppermost position,so that now it can descend anew under the ressure applied to it (withpiston 22 standlng still in the position shown) thereby taking over thedelivery of metal to die 12. The above described cycle is repeated whenthe stock of metal in the cylinder 17 has dropped down to a certainlevel. It will be noted that the diameter of cylinder 18 is larger thanthe diameter of cylinder 17 so that when the former takes charge offeeding cylinder 17 suflicient metal is supplied to take care of feedingthe die 12 at the same time.

The plunger 22 thus acts as supply pump in which the suction issubstituted by an actual charging through opening 25 while the plunger21 carries out the pressing-or squirting operation proper during themajor portion of the time.

To give an idea of the practical range of pressure applied in devices ofthis character it may be assumed that on the pressurepiston is exerted apressure of the order of 2,000,000 kilograms. When piston 22, after itscylinder is charged with fresh liquid metal, is moved in a slightlyhigher pressure is applied to that piston, in order to lift piston 21.However, the outside pressure of 2,000,000 kilograms remains restingupon piston 21. In other words this piston is constantly exposed to auniform outside pressure in contradistinction to piston 22 whose outsidepressure is alternately applied and relieved. Through this arrangementthus a substantially uniform pressure exists in chamber 14, the slightincrease in pres-. sure applied to piston 22 being negligible comparedwith the order of permanent pressure applied to piston 21.

According to my invention the plunger 22 may altogether be replaced by apump tively to each other or whether the plunger 22 stands vertical and21 horizontal.

Various modifications may be made in the device embodying my inventionwithout departing from the spirit and scope thereof I and all suchmodifications are intended to be covered by the appended claims.

I claim as my invention 1.. In a machine for making endless tubes or forproviding cables with a I seamless metallic sheath, the combination of apressing chamber containing the plastic-liquid metal and two cylindersand plungers there in disposed to exert pressure upon said metal onebeing the operating plunger and the other the feeding plunger, theoperating plunger standing constantly under uniform outside pressure andmeans for temporarily separating the feeding plunger from the metal topermit the release of the pressure upon that plunger and the charging ofits cylinder with fresh metal.

2. In a machine for making endless tubes or for providing cables. with aseamless metallic sheath, the combination of a pressing chambercontaining the plastic-liquid metal and several cylinders and plungerstherein adapted to act upon said metal, one being the operating plungerand the other the feeding plunger, the operating plunger standingconstantly under uniform pressure, the feeding plunger being disposed topress metal into said chamber and a slide in the feeding cylinderadapted to close the discharge end of said cylinder for the purpose ofrecharging with fresh metal.

In testimony whereof I aflix my signature.

FERDINAND HANFF.

